In U.S. Pat. No. 6,034,596, incorporated herein by reference, there is disclosed a system for monitoring the pressure and temperature of the tires of a vehicle which generally consists of a set of sensors mountable on the valve stems of the vehicle tires, and a control unit mounted on the vehicle, provided with means for transmitting signals between the control unit and the sensors. Each of such sensors generally includes a housing having a threaded opening, adapted to be threaded onto a tire valve stem to thereby intercommunicate the interior of the tire with the interior of the housing, and pressure and temperature sensors, a microcontroller, a transmitter/receiver and a power supply mounted within such housing. Such system operates in a manner whereby the control unit may selectively activate such sensors, query such sensors for pressure and temperature data which are transmitted to the control unit, process such transmitted data signals and display such processed data for the user.
Although such sensors have been highly effective in sensing pressure and temperature conditions when mounted on the valve stems of tires, and transmitting data signals corresponding to such conditions to the control unit, they present an obstacle when seeking to connect a compressed air line to the valve stems of the tires for adjusting the pressures of the having to remove and replace each sensor. Such requirement of removal and replacement of such sensors each time the inflation pressure of the tire is adjusted has been found to be an inconvenience to the user which renders the use of such sensors less attractive.
It thus is the principal object of the present invention to provide a sensor of the type described which does not require its removal and displacement each time the pressure of the tire on which it is mounted is adjusted.